The present invention relates to drive units for machine applications, such as a punch press or the like, and in particular relates to a multiple speed drive mechanism controlled by a clutch/brake unit of the oil shear type.
Prior art oil shear types of clutch/brake units are definitely described in applicant's prior U.S. Pat. No. 3,696,898, issued Oct. 10, 1982. In many situations, however, it is desireable to provide variable speeds or variable types of movement (such as constant speed versus inching) to a driven mechanism without controlling a motor directly due to a desire to limit any significant period or transient effects. Other considerations may include the lack of ability of a particular motor to provide various speeds or variable types of movement.
The present invention provides the above with the additional advantages prevalent from the utilization of an oil submerged, oil shear interfaced plate and disc construction, such as minimal amount of wear on the plates and discs due to the fact that the torque transmitting function is achieved by the shearing of oil interjacent the plates and discs, low drive inertia, effective oil cooling medium, and compact size. All of the above is provided in the present invention along with a further advantage that the clutch operations are mechanically interlocked and the clutch and brake operations interfaced to prevent damage to the unit due to improper timing.
Other objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.